This invention relates to a variable displacement swash plate type compressor, particularly adapted for use in a vehicular air conditioning system. The compressor includes a pin disposed between a swash plate and a drive shaft that provides a pivot surface during operation of the compressor.
A typical variable displacement swash plate type compressor includes a cylinder block provided with a number of cylinders, a piston disposed in each of the cylinders of the cylinder block, a rotatably supported drive shaft, and a swash plate. The swash plate is rotated by the drive shaft through a hinge mechanism. Rotation of the swash plate reciprocatively drives the pistons. The length of the stroke of the piston is varied by an inclination angle of the swash plate. As the inclination angle of the swash plate changes, the swash plate is caused to slide adjacent the drive shaft, with contact occurring continuously between the swash plate and the drive shaft. The change of the angle of the swash plate should occur as smoothly as possible to assure smooth changes in compressor displacement. The amount and type of contact between the swash plate and the drive shaft must be controlled to minimize wear between the swash plate and drive shaft.
A variety of prior art structures have been disclosed for providing an interface between the swash plate and the drive shaft. One such Structure uses a swash plate wherein its interior surface has been machined. The drive shaft is typically inserted through a hole defined by the interior surface of the swash plate. The interior surface of the swash plate is machined to create two conical surfaces that meet to form an apex near the central portion of the interior surface. The apex contacts the outer surface of the drive shaft. A disadvantage of the structure described is that the machining required creates added expense. In addition, the machined surfaces of the swash plate often require surface hardening creating even more added expense.
Another structure for providing an interface between the swash plate and the drive shaft uses a sleeve slidably mounted on the outer surface of the drive shaft. The outer surface of the sleeve is shaped to conform to an inner bearing surface of the swash plate that defines a hole. The swash plate remains in constant contact with the spherical sleeve. Constant contact increases wear due to the frictional forces acting on the large contact surface. Creating the curved surface on the swash plate to mate with the spherical sleeve requires additional machining, thus adding expense.